On Wed, Nov 28, 2018 at 10:22:07AM -0800, Reinette Chatre wrote:
The user triggers the creation of a pseudo-locked region when writing the requested schemata to the schemata resctrl file. The pseudo-locking of a region is required to be done on a CPU that is associated with the cache on which the pseudo-locked region will reside. In order to run the locking code on a specific CPU the needed CPU has to be selected and ensured to remain online during the entire locking sequence.
At this time the cpu_hotplug_lock is not taken during the pseudo-lock region creation and it is thus possible for a CPU to be selected to run the pseudo-locking code and then that CPU to go offline before the thread is able to run on it.
Fix this by ensuring that the cpu_hotplug_lock is taken while the CPU on which code has to run needs to be controlled. Since the cpu_hotplug_lock is always taken before rdtgroup_mutex the lock order is maintained.
Fixes: e0bdfe8e36f3 ("x86/intel_rdt: Support creation/removal of pseudo-locked region") Signed-off-by: Reinette Chatre reinette.chatre@intel.com Cc: stable@vger.kernel.org
arch/x86/kernel/cpu/resctrl/ctrlmondata.c | 4 ++++ 1 file changed, 4 insertions(+)
This looks like it wants to go in now, right?
If so, pls redo this patch against tip/x86/urgent which has the old filenames, before the resctrl rename and reorg.
Thx.